Skin fastener

ABSTRACT

A fastener for securing adjacent layers of body tissue to each other and being configured and composed of a material so as to emerge from the body tissue after a limited period of time. The fastener includes a backspan and at least two prongs extending from the backspan. Each prong has a tapered tip culminating in a sharp point. The prongs each include a shaft having a cylindrical portion of uniform diameter. In one embodiment, the prong includes a serrated portion having a plurality of notches spaced apart so as to define ridge portions therebetween.

This is a continuation of application Ser. No. 08/097,303, filed on Jul.23, 1993, now abandoned, which is a continuation of Ser. No. 07/817,578,filed on Jan. 7, 1992, now abandoned, which is a continuation of Ser.No. 07/601,335, filed on Oct. 22, 1990, now U.S. Pat. No. 5,108,422.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to surgical fasteners used to join body tissueand more particularly to surgical fasteners which are composed of amaterial and configured to work their way out of body tissue after alimited period of time.

2. Background of the Art

Surgical fasteners have been used in operating procedures to eliminatethe need for suturing, which is both time consuming and inconvenient. Inmany applications the surgeon can use a stapler apparatus, i.e., afastener implanting device loaded with one or more surgical fasteners,to accomplish in a few seconds what would have taken many minutes toperform by suturing. This reduction in operating time reduces blood lossand trauma to the patient.

Surgical fasteners have been in the form of metal staples which are bentby the delivery apparatus to hook together body tissue. Such staples aretypically made from biocompatible metals such as stainless steel alloysor titanium.

Two-part fasteners are also known, as illustrated in U.S. Pat. No.4,506,670, in which a barbed fastener is used in conjunction with aretaining piece to hold the fastener in place.

Typically, the two-part fastener comprises a backspan and two barbedprongs which are engaged and locked into a separate retainer piece. Inuse, the fastener is pressed into the body tissue so that the barbspenetrate the tissue and emerge from the other side where they are thenlocked into the retainer piece. The retainers prevent the fastener fromworking loose from the tissue. The two piece fasteners cannot beunlocked and are not easily removable. For this reason, they must bemade of a bioabsorbable material.

Possible materials include polymers and copolymers of glycolic acid(i.e. hydroxyacetic acid), the cyclic dimer of glycolic acid("glycolide"), lactic acid, the cyclic dimer of lactic acid ("lactide")and related monomers. Polymers and copolymers of the foregoing kind andabsorbable surgical devices made therefrom are well known. See, e.g.,U.S. Pat. Nos. 2,668,162; 2,703,316; 2,758,987; 3,225,766; 3,297,033;3,422,181; 3,531,561; 3,565,869; 3,620,218; 3,626,948; 3,636,956;3,736,646; 3,772,420; 3,773,919; 3,792,010; 3,797,499; 3,839,297;3,867,190; 3,878,284; 3,982,543; 4,060,089; 4,137,921; 4,157,437;4,234,775; 4,237,920; 4,300,565; and 4,523,591; U.K. Patent No. 779,291;D. K. Gilding et al., "Biodegradable polymers for use insurgery--polyglycolic/poly(lactic acid) homo- and co-polymers: 1,Polymer, Volume 20, pages 1459-1464 (1979), and D. F. Williams (ed.)Biocompatibility of Clinical Implant Materials, Vol. II, ch. 9:"Biodegradable Polymers" (1981).

U.S. Pat. No. 4,667,674 to Korthoff et al discloses a two part surgicalfastener comprising a fastener member and a retainer member. Thefastener member has a base, and a pair of prongs extendingperpendicularly from the base. The prongs are spaced inward from therespective ends of the base in order to prevent splaying of the prongs,and to improve hemostasis.

The two piece fasteners require the staple delivery apparatus to haveaccess to both sides of the tissue. Usually, such devices have aU-shaped member into which tissue is inserted. The stapler apparatus hasa fastener holder and an anvil which are pivotally connected at one end,and mounted on the legs of the U-shaped support structure. See, forexample, U.S. Pat. No. 4,402,445 to Green which discloses a surgicalfastener and means for applying same. In a surgical operation, thetissue to be joined is positioned between the fastener holder and theanvil, which contains the fastener retainers. The fasteners are ejectedfrom the holder into the tissue, and the prongs are locked into theretainers.

In some applications, however, it is not possible to have access to bodytissue from two opposite directions. For example, in skin graftingapplications one can only apply fasteners from a stapler positionedabove the skin.

The prior art includes many examples of surgical staplers which do notenclose the body tissue between an anvil and fastener holder. Forexample, surgical staplers such as those described in U.S. Pat. No.3,643,851 and U.S. Pat. No. 4,618,086 approach the skin from onedirection. However, they require the use of staples which are malleableenough to be crimped by an anvil so that the prongs hook into thetissue. Typically, such staples are made of metal and are notbioabsorbable. They must be removed by another device such as a staplerextractor which is not only time consuming but can cause discomfort andpain to the patient. The discomfort and pain in removal of the staplesare especially acute when the fasteners are used in skin grafting a burnvictim. The sensitivity of the burn patient's skin cannot beunderstated; any contact with their skin causes distress, let aloneremoval of fasteners inserted through the skin and embedded inunderlying body tissue.

Single piece barbed fasteners made from bioabsorbable material areknown. U.S. Pat. No. 4,635,637 discloses a fastener having a base memberand two substantially parallel shafts upstanding from the base member,the ends of the shafts each having a barb. The barbed fastener isdisclosed as being useful in the repair of meniscal tissue. Pendingpatent application Ser. Nos. 372,025 filed Jun. 27, 1989, now issuedU.S. Pat. No. 5,089,009 and 314,368 filed Feb. 22, 1989, now issued U.S.Pat. No. 4,994,073 also disclose bioabsorbable fasteners having barbs.If these fasteners are removed, then the patient will suffer from thesame distress as described above with respect to non-bioabsorbablestaples.

The prior art fasteners discussed above were designed with the intentionthat significant vertical support was required. Thus, outwardlyextending barbs were provided on their prongs to ensure that theyremained embedded in the body tissue for a sufficiently long period oftime. However, such barbed fasteners remained in the tissue for a longertime than was necessary. The need therefore exists for a fastener whichremains embedded in the tissue only for a sufficient period of time toallow healing to commence but avoids the discomfort and pain associatedwith the removal of prior fasteners.

SUMMARY OF THE INVENTION

The present invention overcomes the drawbacks and deficiencies of theprior art. The present inventors discovered that in skin grafting, theemphasis is on lateral support across an incision or skin graftinterface to provide sufficient lateral force between adjacent tissuesections. It was found that the vertical support provided by the barbedprongs was unnecessary and that this configuration often required actualremoval of the fasteners, causing pain and discomfort. The presentinvention therefore overcomes the problems of prior art staples andfasteners by significantly limiting the extent of pain the patient willexperience. The present invention achieves this objective by providing asurgical fastener which is composed of a material and configured so asto work its way out of body tissue after a specific period of time orcan be more easily removed beforehand.

The surgical fastener includes a backspan and at least two prongs whichextend from the backspan, preferably perpendicular to the backspan andparallel to each other. Each prong includes a tapered tip portion tofacilitate penetration into the body tissue and is configured to remainin the body for a relatively short period of time. The material of theprong also has a low coefficient of friction to facilitate ejection fromthe body tissue. In one embodiment, substantially the entire shaftportion up to the tapered tip portion has a portion of uniform diameter.That is, there are no barbs on the shaft which would retain the embeddedfastener for a longer period of time than necessary. In otherembodiments, a serrated portion is formed in the uniform-diameter shaftportion to provide additional retention, but less retention than that ofthe barbs of the prior art.

The present invention also provides a method for skin graftingcomprising inserting a plurality of fasteners each having spaced apartprongs wherein at least one prong is devoid of barbs, securing adressing over the fasteners to provide sufficient vertical force to holdthe fasteners for a period of time until healing commences, and removingthe dressing after healing commences wherein a substantial number of thefasteners will be dislodged when the dressing is removed and asubstantial number of the remaining fasteners will be automaticallyejected by the body in a relatively short period of time.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described hereinbelow withreference to the drawings, wherein:

FIG. 1 is an elevational front view of one embodiment of a fastener ofthe present invention;

FIG. 2 is a top view of the fastener of FIG. 1;

FIG. 3 is a side view of the fastener of FIG. 1;

FIG. 4 is an elevational view of another embodiment of the fastener ofthe present invention;

FIG. 5 is an elevational front view of yet another embodiment of afastener of the present invention;

FIG. 6 is a top view of the fastener of FIG. 5;

FIG. 7 is an elevational front view of still another embodiment of afastener of the present invention;

FIG. 8 is a top view of the fastener of FIG. 7;

FIG. 9 is an elevational front view of yet another embodiment of afastener of the present invention;

FIGS. 10a and 10b are sectional perspective views illustrating the useof a fastener of the present invention;

FIG. 11 is a partially cut away elevational view showing an implementfor applying a fastener of the present invention;

FIGS. 12a and 12b are a top view and an elevational from view,respectively, of an embodiment of a fastener of the present inventionlabelled to show one example of the dimensions of a non-serratedfastener which can be utilized; and

FIG. 13 is an enlarged view of an embodiment of a prong of a fastener ofthe present invention labelled to show one example of the dimensions ofa double serrated fastener which can be utilized.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to the drawings, FIGS. 1, 2 and 3 illustrate one embodimentof the skin fastener of the present invention. Fastener 100 includes abackspan 110 and two pronged portions 120 extending from backspan 110.Although the pronged portions 120 are shown parallel to each other andextending substantially perpendicular to backspan 110, as in all theembodiments disclosed herein, one or both of the pronged portions 120can alternately be secured at a different angle to backspan 110 toextend inwardly towards each other or outwardly away from each other. Inthis embodiment, each prong 120 has a shaft portion 121 illustrativelycylindrical in configuration, and a tapered tip portion 124 whichculminates in a sharp point 125 at the distal end to facilitatepenetration of body tissue. Prongs 120 also include a serrated portionhaving ridges 122 alternating with recessed notch portions 123. Theserrations extend circumferentially around shaft 121. Fastener 100 is adouble serrated prong fastener in that there are two ridge portions 122on each prong. The serrations provide additional frictional means tohold the fastener in body tissue for a longer period of time than if noserrations were present. Nevertheless, these serration do not constitutebarbs. That is, the ridges do not extend radially beyond thecircumferential surface of the cylindrical shaft portion 121, and theydo not prevent fastener 100 from gradually working its way out of bodytissue within a specific period of time. By not having barbs, thefasteners can also be more easily removed. The diameter of the taperedtip portion 124 does not exceed the diameter of the shaft portion 121.The base portion of each prong 120 may be provided with a carved surface126.

In the embodiment shown in FIG. 1, the backspan 110 extends lengthwise agreater distance than the distance between prongs 120. In other words,thug embodiment possesses an overlap portion 112 which extends the areaof tissue which is being held down and is an optional feature of thisinvention since alternately the backspan 110 can terminate at the prongs120. Members 111 at each end of the fastener backspan 110 can optionallybe provided to provide a guide means to maintain the proper orientationof the fastener inside a fastener applying instrument while the fasteneris being implanted.

FIG. 4 illustrates an embodiment of the fastener of the presentinvention having a single serration. As with the double serratedembodiment 100, single serrated fastener 200 includes backspan 210 andprongs 220 having a shaft portion 221 and circumferential serrationsincluding ridge 222 and recessed notch portions 223. Each prong 220 offastener 200 also includes a tapered tip portion 224 having a sharppoint 225 at its distal end. The backspan 210 can also include overlapportions 212 to increase the surface area of tissue held down and guidemembers 211 for engagement by a fastener instrument. Fastener 200differs from fastener 100 in that it includes a single ridge 222 insteadof double ridges on each prong. Thus the retention period of fastener200 will be less than that of fastener 100. As with the previousembodiment, the ridge 222 does not extend radially beyond thecircumferential surface of the cylindrical shaft portion. Also, it maybe noted that the serrated portion can optionally be located relativelyfurther up the half portion as shown so that there is cylindrical shaftportion 221 below as well as above the serrated portion.

Fastener 300 of FIGS. 5 and 6 illustrates an embodiment of the presentinvention which does not have guide members. Parallel prongs 320illustratively extend perpendicularly from backspan 310. Each prong 320has a shaft portion 321 preferably circular in cross section. Prongs 320each have a serrated area with a ridge 322 and notches 323. The prong320 includes a tip portion 324 terminating in sharp point 325. Thebackspan 310 includes overlap portion 312. Fastener 300, as shown, doesnot include a guide member at the ends of the backspan such as inmembers 111 and 211.

FIGS. 7 and 8 illustrate another embodiment of the present invention.Fastener 400 includes a backspan 410 and pair of prongs 420 extendingfrom the backspan 410. In this illustrated embodiment, prongs 420 areparallel to one another and extend substantially perpendicular tobackspan 410. Each prong has a shaft portion 421 and a tapered tipportion 424 having a sharp distal point 425. Unlike the previousembodiments, fastener 400 does not include serrations so that each shaftportion 421 maintains a substantially smooth continuous surfacethroughout its length M. Thus, fastener 400 is configured to remainimplanted for a shorter period of time than the serrated versions of thefastener shown in FIGS. 1-6. Overlap portion 412 is an optional feature.

Referring to FIG. 7, each prong 420 has an overall length L and thesmooth cylindrical shaft portion 421 of each prong 420 has length N andthe tapered portion 424 has length M.

Fastener 400 can be fabricated in a variety of sizes. In a longerpronged version, the length M of the shaft portion 421 is about one-halfof the overall prong length L, and in a shorter pronged version shaftportion 421 is about one third of the overall prong length L. (Note thatfasteners 100, 200 and 300 described above can also be fabricated in avariety of sizes including a long pronged version and a short prongedversion.) Clearly, the ratio of the lengths of the shaft portions, tipportion and overall prong can differ from that described above toaccommodate various uses of the fasteners.

FIG. 9 illustrates yet another embodiment of the present invention inwhich fastener 700 has a backspan 710 and a pair of prongs 720, 720'.Backspan 710 is shown with the optional features of the overlap portion712 and guide members 711. In this embodiment, prong 720' is devoid ofserrations and has a continuous smooth surface extending along thelength of shaft portion 721' (from backspan 710 to tapered tip portion724'.) Prong 720 has a double serration formed by ridges 722 andrecesses 723 disposed in shaft portion 721. Tapered portion 724terminates in distal point 725. Due to this configuration, prong 720'has increased frictional characteristics compared to prong 720 and willtherefore provide increased holding force of the tissue. This is usefulto accommodate differences in tissue type or tissue condition (e.g.health) between adjacent tissue sections to be joined. Thus, theconfiguration of the prongs of FIG. 9 are suitable when one of thetissue sections requires additional vertical retention force. Clearly,other variations on the number of serrations on each individual prong ofthe fastener is contemplated by the present invention, and will dependon its use. This advantageously improves the versatility of the fastenerby enabling it to accommodate differences in the tissue regions throughwhich it is inserted and adapted to be retained. That is, if additionalretention properties are required for only one prong, then additionalserrations can be provided on that prong.

FIGS. 10a, 10b and 11 illustrate one me of the fastener of the presentinvention. As shown, the method of skin grafting utilizing the prongedfasteners involves placing a grafted layer of skin 520 adjacent originalskin portion 530. Fasteners 500, which can be any of the previouslydescribed embodiments, but is shown as a version with no serrations forconvenience, are implanted across the interface 550 between a graftedlayer of skin 520 and original skin 530. Prongs 502 penetrate theunderlying tissue 510 and backspan 501 overlies the upper surface oflayers 520 and 530. The fastener 500 thus provides sufficient lateralforce across the interface 550. As shown, the prongs of the fastenerextend substantially in the same direction. Each tip portion 504 tapersto sharp point 505 to facilitate implementation. In FIG. 10b a graftedlayer of skin 550 is placed over an existing wound and skin fasteners500 are applied circumferentially around the skin layer 550 to fasten itto underlying skin layer 560. Note one of the prongs of the fastenerextends into one skin portion and the other prong extends into the otherskin portion.

In use, after insertion of the fasteners, gauze dressing 540 is appliedover the grafted area and secured by surgical tape, or other suitablemeans. The gauze dressing provides vertical holding means for thefasteners. Thus, the fasteners principally function to secure the tissuelayers 520 and 530 laterally across interface 550. Barbs are not neededto secure grafted layer 520 into base layer 510 since sufficientvertical force is provided by the gauze 540 for the limited time periodnecessary for healing to commence. That is, the fasteners 500 are onlyrequired to in the tissue for a period of time sufficient for healing tobegin: typically three to thirteen days and preferably only three days.The smooth surfaced embodiment of the present invention, i.e., theembodiment as illustrated in FIGS. 7 and 8, will typically remainimplanted for about 3 to 6 days, although the time periods will differdepending on the configuration of the prong, its material compositionand the type and condition of the tissue in which it is embedded as willbe described below. The serrated embodiments, on the other hand, willtypically remain implanted for a longer period of time and about 5 to 10days, although the time periods will also differ depending on theaforementioned variables. The fasteners can be ejected by the body orduring routine contact such as dressing changes or sponge baths. Thisadvantageously not only saves true which would otherwise be required toremove each fastener but reduces the patient's discomfort and paincaused by such removal. By not having outwardly extending barbs, thefasteners can also be removed more easily and will inflict less painupon the patient.

An apparatus suitable for applying the skin fasteners of the presentinvention is disclosed in FIG. 11. The apparatus however, is illustratedfor the readers convenience and is not part of the present invention. Afastener applying instrument 600 includes a nose portion 610 having afiring chamber 620 defined by walls 621 and terminating in exit opening622 at the distal end of the instrument. When used, the distal end ofthe instrument is positioned adjacent the body tissue to be fastenedsuch that fastener 500 will be implanted into the tissue upon exitingfrom opening 622. Fastener 500 is slidably positioned in the interior ofthe firing chamber 620 such that when pusher bar 630 moves distally(i.e. towards exit opening 622), fastener 600 is driven out of the exitopening 622 and into the body tissue. Instruments for holding one ormore fasteners and for driving pusher bars are well known to those withskill in the art.

As noted above, one factor affecting the retention period of thefastener is its configuration. The number of serrations formed in theprong will affect the retention time of the fastener; the retention timeincreasing as the number of serrations increase. The width and length ofthe prongs will also affect retention time; i.e. the longer fastenertaking a longer time to be forced out by the body became of the longerdistance it needs to travel through the tissue.

The material utilized for the fastener will also affect the retentionperiod. The desired properties of the material include resiliency,sufficient rigidity to provide lateral force but not too brittle so asto easily break during use. Both bioabsorbable and non-bioabsorbablematerials can be urged. Examples of bioabsorbable material includehomopolymers or copolymers of lactide, glycolide, polydioxanone,trimethylene carbonate, polyethylene oxide or other bioabsorbablepolymer materials or blends of these respective copolymers. Onepreferred material is made of a copolymer of lactide and glycolide madefrom approximately 25% m glycolide and 75% m lactide blended with ahomopolymer of polyglycolide so the total composition is composed ofapproximately 42% glycolide. Another bioabsorbable resinous material forconstructing the fasteners is disclosed in U.S. Pat. No. 4,523,591 toKaplan et al, herein incorporated by reference. Clearly, the materialsdisclosed in the patents and literature listed in the Background sectionof this application can also be utilized. Non bioabsorbable materialscontemplated include any implantable material such as polyester,polypropylene, or polyethylene. Additives can also be mixed with thesematerials to provide increased stiffening. Materials providing a wettedsurface with a low coefficient of friction will facilitate ease ofwithdrawal from the tissue. Clearly, materials having a highercoefficient of friction will have a relatively longer retention period.

Another factor which can influence the retention period is theinteraction between the type of material and the tissue during healing.Increased tissue reactions such as swelling can expedite forcing thefastener towards the surface and out of the tissue. The thickness andtype of tissue will also be a factor in retention of the fastener.

The fasteners of the invention can be made of various sizes depending ontheir use. For example, the length of the backspan and prongs can rangefrom less than one millimeter to over one inch in length, depending onthe type of tissue in which they are used. For example, the face andfinger regions require a shorter shaft while the abdomen region mayrequire a longer shaft. The length and width of the fastener is afunction of the tissue used as well as the material.

Set forth below are several examples of dimensions of the fasteners.These dimensions provide only a few examples of the virtually limitlessnumber of sizes in which the fasteners can be formed. Therefore, itshould be understood that the following examples of the presentinvention illustrate only possible dimensions of the fastener, and thefasteners of the present invention are in no way limited to thesedimensions. Reference to FIGS. 12a, 12b and 13 will assist inunderstanding the dimensions set forth below.

In one version the overall length T of backspan 910 of fastener 900(FIG. 12a), ranges from 0.3985 to 0.3925 inches. Length R ranges from0.248 to 0.252 inches and length S ranges from 0.2795 to 0.2825 inches.Length J (FIG. 12b) of fastener 900 ranges from 0.030 to 0.032 inches;length N of shaft portion 921 ranges from 0.082 to 0.084 inches; lengthO of tapered tip portion 925 ranges from 0.082 to 0.084 inches andlength P of prong 920 ranges from 0.164 to 0.168 inches.

In a shorter version of fastener 900, length N can range from 0.042 to0.044, length O from 0.082 to 0.084 and length P from 0.124 to 0.128inches.

The prong 820 of the fastener of FIG. 13 has a shaft portion 821 oflength A and a tapered tip portion 824 of length B, each ranging from0.082 to 0.084 inches. Diameter F of shaft portion 821 ranges from 0.030to 0.032 inches. The height D of each notch 823 ranges from 0.008 to0.011 inches, the depth G of each notch ranges from 0.005 to 0.007inches, and the height E of each ridge 822 ranges from 0.005 to 0.007inches. Angle H measures 21° 10'.

It will be understood that the foregoing is only illustrative of theprinciples of the invention and that various modifications can be madeby those skilled in the art without departing from the scope and spiritof the present invention.

What is claimed is:
 1. A method of skin grafting utilizing at least onebioabsorbable fastener having a pair of prongs extending from abackspan, each prong having a penetrating tip and a shaft portion; themethod comprising the steps of:a. obtaining a first portion of skin froma portion of the patient's body; b. placing said first portion of skinadjacent a second portion of skin; c. providing at least onebioabsorbable fastener having a recessed portion in the shaft portion,wherein said at least one fastener is composed in whole or in part of ahomopolymer or copolymer of glycolide, lactide, polydioxanone,trimethylene carbonate, polyethylene oxide or blends thereof; d.inserting said at least one bioabsorbable fastener having the recessedportion formed in the shaft portion such that said prongs extend throughsaid first portion of skin and a portion of skin extends into therecessed portion, said prongs positioned therein without engaging aretainer; and e. placing a bandage over the backspan of said at leastone fastener to apply a force to said fastener.
 2. A method as recitedin claim 1, wherein said at least one fastener is configured anddimensioned to be ejected from the body after a period of time.
 3. Amethod of skin grafting utilizing at least one bioabsorbable fastenerhaving first and second prongs extending from a backspan, the methodcomprising the steps of:a. obtaining a first portion of skin from aportion of the patient's body; b. placing said first portion of skinadjacent a second portion of skin; c. inserting said at least onebioabsorbable fastener such that said first prong extends into saidfirst skin portion and said second prong extends into said second skinportion, said at least one fastener positioned therein without engaginga retainer; and d. placing a bandage over the backspan of said at leastone fastener to apply a force to said fastener.
 4. A method according toclaim 3, wherein said at least one fastener is composed in whole or inpart of a homopolymer or copolymer of glycolide, lactide, polydioxanone,trimethylene carbonate, polyethylene oxide or blends thereof.
 5. Amethod as recited in claim 3, further comprising the step of leavingsaid at least one fastener in said skin portion, said at least onefastener being configured and dimensioned to be ejected from the bodyafter a period of time.
 6. A method of skin grafting utilizing at leastone bioabsorbable fastener having first and second prongs extending froma backspan, the method comprising the steps of:a. obtaining a firstportion of skin from a portion of the patient's body; b. placing saidfirst portion of skin adjacent a second portion of skin; c. providing atleast one bioabsorbable fastener devoid of barbs; and d. positioningsaid at least one bioabsorbable fastener such that said first prongextends into said first skin portion in a first direction and saidsecond prong extends into said second skin portion in said firstdirection, said at least one fastener positioned therein withoutengaging a retainer; and e. leaving said at least one fastener in saidskin portion such that said first and second prongs extend substantiallyin said first direction and such that said at least one fastener beingdevoid of barbs can be ejected from the body after a period limited oftime.
 7. A method according to claim 6 further comprising the step ofplacing a bandage over the backspan of said at least one fastener toapply a force to said fastener.
 8. A method as recited in claim 7wherein said at least one fastener is configured and dimensioned to beejected from the body after a period of time.